scholarly journals Emission of volatile halogenated organic compounds over various landforms at the Dead Sea

2018 ◽  
Author(s):  
Moshe Shechner ◽  
Alex Guenther ◽  
Robert Rhew ◽  
Asher Wishkerman ◽  
Qian Li ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Bare Soil ◽  
Dead Sea ◽  
Salt Lakes ◽  
Saline Soils ◽  
Emission Rates ◽  
Methyl Halides ◽  
Halogenated Organic Compounds ◽  
Mixing Ratios ◽  
Volatile Halogenated Organic Compounds

Abstract. Volatile halogenated organic compounds (VHOCs), such as methyl halides (CH3X; X = Br, Cl and I) and very short-lived halogenated substances (VSLS; CHBr3, CH2Br2, CHBrCl2, C2HCl3, CHCl3 and CHBr2Cl) are well known for their significant influence on ozone concentrations and oxidation capacity of the troposphere and stratosphere, and for their key role in aerosol formation. Insufficient characterization of the sources and emission rate of VHOCs limits our present ability to understand and assess their impact in both the troposphere and the stratosphere. Over the last two decades several natural terrestrial sources for VHOCs, including soil and vegetation, have been identified, but our knowledge about emission rates from these sources and their responses to changes in ambient conditions remains limited. Here we report measurements of the mixing ratios and the fluxes of several chlorinated and brominated VHOCs from different landforms and vegetated sites at the Dead Sea during different seasons. Fluxes were highly variable but were generally positive (emissive), corresponding with elevated mixing ratios for all of the VHOCs investigated in the four investigated site types – bare soil, coastal, cultivated and natural vegetated sites – except for fluxes of CH3I and C2HCl3 over the vegetated sites. In contrast to previous reports, we also observed emissions of brominated trihalomethanes, with net molar fluxes ordered as follows: CHBr2Cl > CHBr3 > CHBrCl2 > CHCl3. This finding can be explained by the enrichment of soil with Br. Correlation analysis, in agreement with recent studies, indicated common controls for the formation and emission of all the above trihalomethanes but also for CH2Br2. Also in line with previous reports, we observed elevated emissions of CHCl3 and C2HCl3 from mixtures of soil and different salt-deposited structures; the high correlations of flux with methyl halides, and particularly with CH3I, suggested that at least CH3I is also emitted via similar mechanisms or is subjected to similar controls. Overall, our results indicate elevate emission of VHOCs from bare soil under semi-arid conditions. Along with other recent studies, our findings point to the strong emission potential of a suite of VHOCs from saline soils and salt lakes, and call for additional studies of emission rates and mechanisms of VHOCs from saline soils and salt lakes.

scholarly journals Emission of volatile halogenated organic compounds over various Dead Sea landscapes

2019 ◽  
Vol 19 (11) ◽  
pp. 7667-7690 ◽  
Author(s):  
Moshe Shechner ◽  
Alex Guenther ◽  
Robert Rhew ◽  
Asher Wishkerman ◽  
Qian Li ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Bare Soil ◽  
Dead Sea ◽  
Salt Lakes ◽  
Saline Soils ◽  
Emission Rates ◽  
Methyl Halides ◽  
Halogenated Organic Compounds ◽  
Mixing Ratios ◽  
Volatile Halogenated Organic Compounds

Abstract. Volatile halogenated organic compounds (VHOCs), such as methyl halides (CH3X; X is Br, Cl and I) and very short-lived halogenated substances (VSLSs; bromoform – CHBr3, dibromomethane – CH2Br2, bromodichloromethane – CHBrCl2, trichloroethylene – C2HCl3, chloroform – CHCl3 – and dibromochloromethane – CHBr2Cl) are well known for their significant influence on ozone concentrations and oxidation capacity of the troposphere and stratosphere and for their key role in aerosol formation. Insufficient characterization of the sources and the emission rate of VHOCs limits our ability to understand and assess their impact in both the troposphere and stratosphere. Over the last two decades, several natural terrestrial sources for VHOCs, including soil and vegetation, have been identified, but our knowledge of emission rates from these sources and their responses to changes in ambient conditions remains limited. Here we report measurements of the mixing ratios and fluxes of several chlorinated and brominated VHOCs from different landscapes and natural and agricultural vegetated sites at the Dead Sea during different seasons. Fluxes were generally positive (emission into the atmosphere), corresponding to elevated mixing ratios, but were highly variable. Fluxes (and mixing ratios) for the investigated VHOCs ranged as follows: CHBr3 from −79 to 187 nmol m−2 d−1 (1.9 to 22.6 pptv), CH2Br2 from −55 to 71 nmol m−2 d−1 (0.7 to 19 pptv), CHBr2Cl from −408 to 768 nmol m−2 d−1 (0.4 to 11 pptv), CHBrCl2 from −29 to 45 nmol m−2 d−1 (0.5 to 9.6 pptv), CHCl3 from −577 to 883 nmol m−2 d−1 (15 to 57 pptv), C2HCl3 from −74 to 884 nmol m−2 d−1 (0.4 to 11 pptv), methyl chloride (CH3Cl) from -5300 to 10,800 nmol m−2 d−1 (530 to 730 pptv), methyl bromide (CH3Br) from −111 to 118 nmol m−2 d−1 (7.5 to 14 pptv) and methyl iodide (CH3I) from −25 to 17 nmol m−2 d−1 (0.4 to 2.8 pptv). Taking into account statistical uncertainties, the coastal sites (particularly those where soil is mixed with salt deposits) were identified as sources of all VHOCs, but this was not statistically significant for CHCl3. Further away from the coastal area, the bare soil sites were sources for CHBrCl2, CHBr2Cl, CHCl3, and probably also for CH2Br2 and CH3I, and the agricultural sites were sources for CHBr3, CHBr2Cl and CHBrCl2. In contrast to previous reports, we also observed emissions of brominated trihalomethanes, with net molar fluxes ordered as follows: CHBr2Cl > CHCl3 > CHBr3 > CHBrCl2 and lowest positive flux incidence for CHCl3 among all trihalomethanes; this finding can be explained by the soil's enrichment with Br. Correlation analysis, in agreement with recent studies, indicated common controls for the emission of CHBr2Cl and CHBrCl2 and likely also for CHBr3. There were no indications for correlation of the brominated trihalomethanes with CHCl3. Also in line with previous reports, we observed elevated emissions of CHCl3 and C2HCl3 from mixtures of soil and different salt-deposited structures; the flux correlations between these compounds and methyl halides (particularly CH3I) suggested that at least CH3I is also emitted via similar mechanisms or is subjected to similar controls. Overall, our results indicate elevated emission of VHOCs from bare soil under semiarid conditions. Along with other recent studies, our findings point to the strong emission potential of a suite of VHOCs from saline soils and salt lakes and call for additional studies of emission rates and mechanisms of VHOCs from saline soils and salt lakes.

Determination of Very Volatile Halogenated Organic Compounds in Water by Means of Direct Head-Space Analysis

1978 ◽  
Vol 11 (5) ◽  
pp. 437-448 ◽  
Author(s):  
G. J. Piet ◽  
P. Slingerland ◽  
F. E. De Grunt ◽  
M. P. M. Heuvel ◽  
B. C. J. Zoeteman
Keyword(s):  
Organic Compounds ◽  
Halogenated Organic Compounds ◽  
Space Analysis ◽  
Head Space ◽  
Direct Head ◽  
Volatile Halogenated Organic Compounds ◽  
Head Space Analysis

Radiocarbon content of synthetic and natural semi-volatile halogenated organic compounds

2002 ◽  
Vol 120 (2) ◽  
pp. 163-168 ◽  
Author(s):  
Christopher M. Reddy ◽  
Li Xu ◽  
Timothy I. Eglinton ◽  
Jan P. Boon ◽  
D.John Faulkner
Keyword(s):  
Organic Compounds ◽  
Halogenated Organic Compounds ◽  
Volatile Halogenated Organic Compounds

scholarly journals From emissions to ambient mixing ratios: on-line seasonal field measurements of volatile organic compounds over a Norway spruce dominated forest in central Germany

2013 ◽  
Vol 13 (11) ◽  
pp. 30187-30232 ◽  
Author(s):  
E. Bourtsoukidis ◽  
J. Williams ◽  
J. Kesselmeier ◽  
S. Jacobi ◽  
B. Bonn
Keyword(s):  
Volatile Organic Compounds ◽  
Norway Spruce ◽  
Organic Compounds ◽  
Atmospheric Chemistry ◽  
Temperature Dependency ◽  
Emission Rates ◽  
Temperature Dependent ◽  
Central Germany ◽  
Mixing Ratios ◽  
Volatile Organic

Abstract. Biogenic volatile organic compounds (BVOC) are substantial contributors to atmospheric chemistry and physics and demonstrate the close relationship between biosphere and atmosphere. Their emission rates are highly sensitive to meteorological and environmental changes with concomitant impacts on atmospheric chemistry. We have investigated seasonal isoprenoid and oxygenated VOC (oxVOC) fluxes from a Norway spruce (Picea abies) tree in Central Germany and explored the emission responses under various atmospheric conditions. Emission rates were quantified by using dynamic branch enclosure and Proton Transfer Reaction–Mass Spectrometry (PTR-MS) techniques. Additionally, ambient mixing ratios were derived through application of a new box model treatment on the dynamic chamber measurements. These are compared in terms of abundance and origin with the corresponding emissions. Isoprenoids govern the BVOC emissions from Norway spruce, with monoterpenes and sesquiterpenes accounting for 50.8 ± 7.2% and 19.8 ± 8.1% respectively of the total emissions. Normalizing the VOC emission rates, we have observed a trend of reduction of carbon containing emissions from April to November, with an enhancement of oxVOC. Highest emission rates were observed in June for all measured species, with the exception of sesquiterpenes that were emitted most strongly in April. We exploit the wide range of conditions experienced at the site to filter the dataset with a combination of temperature, ozone and absolute humidity values in order to derive the emission potential and temperature dependency development for the major chemical species investigated. A profound reduction of monoterpene emission potential (E30) and temperature dependency (β) was found under low temperature regimes, combined with low ozone levels (E30MT, LTLO3=56 ± 9.1 ng g(dw)−1 h−1, βMT,LTLO3=0.03±0.01 K−1) while a combination of both stresses was found to alter their emissions responses with respect to temperature substantially (E30MT,HTHO3=1420.1 ± 191.4 ng g(dw)−1 h−1, βMT,HTHO3=0.15 ± 0.02 K−1). Moreover, we have explored compound relationships under different atmospheric condition sets, addressing possible co-occurrence of emissions under specific conditions. Finally, we evaluate the temperature dependent algorithm that seems to describe the temperature dependent emissions. Highest emission deviations were observed for monoterpenes and these emission fluctuations were attributed to a fraction which is triggered by an additional light dependency.

Measurements of atmospheric halogenated organic compounds during polar night

2021 ◽  
Author(s):  
Katarina Abrahamsson ◽  
Patric Simoes Pereira ◽  
Adela Dumitrascu ◽  
Carlos A. Cuevas ◽  
Alfonso Saiz-Lopez
Keyword(s):  
Surface Water ◽  
Organic Compounds ◽  
High Arctic ◽  
Arctic Climate ◽  
The Arctic ◽  
Polar Night ◽  
Halogenated Organic Compounds ◽  
Atmospheric Processes ◽  
Volatile Halogenated Organic Compounds ◽  
Winter Time

<p>A number of volatile halogenated organic compounds (halocarbons) have been shown to be emitted from the oceans and more lately from sea ice. Several of these contribut to halogens to the troposphere which are involved in a number of atmospheric processes amongst these the destruction of ozone and the speciation of mercury. Historically, most measurements in the Arctic has been performed during summer conditions, but no campaign to the high Arctic has been performed during winter time.</p><p>Here we present the first suite of measurements of halocarbons in air and surface water during polar night during the MOSAiC (Multi-disciplinary Drifting Observatory for the Study of the Arctic Climate) expedition from October 2019 to May 2020. Comparisons will be made with measurements during summer in August 2018.</p>

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